Process for preparing an ion-exchange composite material comprising a specific polymer matrix and a filler consisting of ion-exchange particles

Abstract

The invention relates to a process for preparing a composite material comprising a fluorinated polymeric matrix and a filler consisting in ion exchange inorganic particles comprising a step for in situ synthesis of said particles within the polymeric matrix, said matrix comprising at least one first copolymer comprising at least two types of fluorinated recurrent units, a type of which bears at least one pendant maleic anhydride group.

The invention claimed is: 
     
       1. A process for preparing a composite material comprising a fluorinated polymeric matrix and a filler consisting of ion exchange inorganic particles comprising a step for synthesizing in situ said particles within the polymeric matrix, said matrix comprising at least one first copolymer consisting of a copolymer comprising at least two types of fluorinated recurrent units, one type of which bears at least one pendant maleic anhydride group. 
     
     
       2. The process according to  claim 1 , wherein the in situ synthesis step is carried out in an extruder. 
     
     
       3. The process according to  claim 1 , wherein the in situ synthesis step is carried out with a sol-gel method. 
     
     
       4. The process according to  claim 1 , wherein the in situ synthesis step is carried out with a sol-gel method comprising the following operations:
 an operation for putting the first copolymer and if necessary the constitutive distinct (co)polymer(s) of the matrix, in contact with one or several precursors of the inorganic particles, said precursor(s) fitting the following formula (I):
   (X) y-n -M-(R) n   (I)
 
 
 wherein: 
 M is a metal element or a metalloid element; 
 X is a hydrolyzable chemical group; 
 R is an ion exchange chemical group or a precursor group of an ion exchange chemical group; 
 y corresponds to the valency of the element M; and 
 n is an integer ranging from 0 to (y−1); 
 a hydrolysis-condensation operation of said precursor(s), in return for which inorganic particles are obtained, resulting from the hydrolysis-condensation of said precursors; 
 in the case when R is a precursor group of an ion exchange chemical group, an operation for transforming the precursor group into an ion exchange chemical group or, in the case when n=0, an operation for functionalizing said particles with ion exchange chemical groups. 
 
     
     
       5. The process according to  claim 1 , wherein the in situ synthesis step is carried out with a sol-gel method comprising the following steps:
 an operation for hydrolysis of one or several precursors of inorganic particles of the following formula (I):
   (X) y-n -M-(R) n   (I)
 
 
 wherein: 
 M is a metal element or a metalloid element; 
 X is a hydrolyzable chemical group; 
 R is an ion exchange chemical group or a precursor group of an ion exchange chemical group; 
 y corresponds to the valency of element M; and 
 n is an integer ranging from 0 to (y−1); 
 an operation for putting the hydrolyzate obtained in the preceding step in contact with the first copolymer and if necessary the distinct (co)polymer(s) entering the composition of the matrix; 
 an operation for heating the resulting mixture to an effective temperature for generating transformation of the hydrolyzate into inorganic particles; 
 in the case when R is a precursor group of an ion exchange chemical group, an operation for transforming the precursor group into an ion exchange chemical group or, in the case when n=0, an operation for functionalizing said particles with ion exchange chemical groups. 
 
     
     
       6. The process according to  claim 4 , wherein M is silicon, titanium, aluminium, germanium, tin or lead. 
     
     
       7. The process according to  claim 4 , wherein X is an —OR′ group or a halogen atom, R′ representing an alkyl group. 
     
     
       8. The process according to  claim 4 , wherein R is a cation exchange group of formula —R 2 —Z 1 , wherein:
 R 2  is a simple bond, a linear or branched alkylene group, and optionally for which one or several hydrogen atoms are substituted with a halogen atom, such as fluorine, or R 2  is a cyclic hydrocarbon group; 
 Z 1  is a group —SO 3 H, —PO 3 H 2 , —CO 2 H, optionally as salts. 
 
     
     
       9. The process according to  claim 4 , wherein R is a group of formula —R 2 —Z 3 , wherein:
 R 2  is a simple bond, a linear or branched alkylene group, and optionally for which one or several hydrogen atoms are substituted with a halogen atom, such as fluorine, or R 2  is a cyclic hydrocarbon group; 
 Z 3  is a precursor group of a group Z 1  wherein Z 1  is a group —SO 3 H, —PO 3 H 2 , —CO 2 H, optionally as salts. 
 
     
     
       10. The process according to  claim 9 , wherein the precursor is a precursor of the following formula (II):
   (OR′) 4-n —Si—(R) n   (II)
 
 wherein: 
 R′ is an alkyl group; 
 R corresponds to the formula —R 2 —Z 3 , R 2  being a linear or branched alkylene group, comprising from 1 to 30 carbon atoms, and optionally for which one or several hydrogen atoms are substituted with a halogen atom, such as fluorine and Z 3  is a precursor group of a group Z 1  wherein Z 1  is a group —SO 3 H, —PO 3 H 2 , —CO 2 H, optionally as salts; 
 n is an integer ranging from 1 to 3. 
 
     
     
       11. The process according to  claim 10 , wherein the precursor is mercaptopropyltriethoxysilane of formula:
   HS—(CH 2 ) 3 —Si(OCH 2 CH 3 ) 3 .
 
 
     
     
       12. The process according to  claim 4 , wherein the precursor(s) are used in combination with a precondensate comprising recurrent units of the following formula (III):
     M(X) y-2     (III)
 
 wherein: 
 M is a metal or metalloid element; 
 X is a hydrolyzable chemical group; 
 y corresponds to the valency of element M. 
 
     
     
       13. The process according to  claim 1 , wherein the matrix exclusively consists of said first copolymer. 
     
     
       14. The process according to  claim 1 , wherein the matrix comprises, in addition to said first copolymer, at least one other (co)polymer distinct from said first copolymer. 
     
     
       15. The process according to  claim 14 , wherein the distinct (co)polymer is selected from among fluorinated thermoplastic polymers. 
     
     
       16. The process according to  claim 15 , wherein the fluorinated thermoplastic polymers are not ion exchange polymers, said fluorinated thermoplastic polymers selected from among polytetrafluoroethylenes (PTFE), poly(vinylidene fluoride)s (PVDF), fluorinated ethylene-propylene copolymers (FEP), copolymers of ethylene and tetrafluoroethylene (ETFE), copolymers of vinylidene fluoride and hexafluoropropene (PVDF-HFP) and mixtures thereof. 
     
     
       17. The process according to  claim 1 , wherein the first copolymer consists in a copolymer comprising, in addition to the fluorinated recurrent unit bearing the pendant maleic anhydride group, a recurrent unit fitting the following formula (V): 
       
         
           
           
               
               
           
         
       
       wherein R 3 , R 4 , R 5  and R 6  represent, independently of each other, a hydrogen atom, a halogen atom, a perfluoroalkyl group or a perfluoroalkoxy group, provided that at least one of the groups R 3  to R 6  represents a fluorine atom, a perfluoroalky group or a perfluoroalkoxy group. 
     
     
       18. The process according to  claim 17 , wherein a particular recurrent unit covered by the general definition of recurrent units of formula (V) corresponds to a recurrent unit of the following formula (VII): 
       
         
           
           
               
               
           
         
       
     
     
       19. The process according to  claim 1 , wherein the first copolymer further comprises a recurrent unit of the following formula (IX): 
       
         
           
           
               
               
           
         
       
     
     
       20. The process according to  claim 1 , wherein the fluorinated recurrent unit comprising a pendant maleic anhydride group is a recurrent unit of the following formula (X): 
       
         
           
           
               
               
           
         
       
       wherein R 7  to R 9  represent, independently of each other, a hydrogen atom, a halogen atom, a perfluoroalkyl group. 
     
     
       21. The process according to  claim 20 , wherein a particular recurrent unit covered by the general definition of recurrent units of formula (X) corresponds to a recurrent unit of the following formula (XI): 
       
         
           
           
               
               
           
         
       
     
     
       22. The process according to  claim 1 , wherein the first copolymer is a copolymer comprising a first type of recurrent unit of formula (VII) 
       
         
           
           
               
               
           
         
       
       a second type of recurrent unit of formula (IX) 
       
         
           
           
               
               
           
         
       
       and a third type of recurrent unit of formula (XI) 
       
         
           
           
               
               
           
         
       
     
     
       23. The process according to  claim 1 , wherein the first copolymer comprises, except for the fluorinated recurrent units comprising a pendant maleic anhydride group, one or several recurrent units with formula(e) identical with that(those), if necessary, of the distinct (co)polymers entering the composition of the fluorinated polymer matrix. 
     
     
       24. A composite material comprising a fluorinated polymeric matrix comprises at least one first copolymer consisting of a copolymer comprising at least two types of fluorinated recurrent units, one type of which bears at least one pendant maleic anhydride group, and a filler consisting of ion exchange inorganic particles. 
     
     
       25. An electrolytic membrane for a fuel cell comprising a material as defined in  claim 24 .